A mid level disturbance along with thermal boundaries associated with earlier cloud cover helped produce conditions favorable for strong thunderstorms over the Southeast during peak heating hours.
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The episode as NWS CHS wrote it up.
A mid level disturbance along with thermal boundaries associated with earlier cloud cover helped produce conditions favorable for strong thunderstorms over the Southeast during peak heating hours.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Charleston, SC wrote its last area forecast discussion before the first event at Aug 20, 2:44 PM EST, 3 hours 3 minutes earlier.
Area Forecast Discussion National Weather Service Charleston SC 344 PM EDT SAT AUG 20 2016 .SYNOPSIS... A trough of low pressure will persist inland into Sunday. A cold front will move south through the area early Monday and dissipate Tuesday. High pressure will build from the north behind the front and prevail into next weekend. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Rest of the afternoon: Current convective development back across central Georgia seems to be immediately ahead of the weak and subtle shortwave noted on water vapor imagery. This feature appears to remain weak as it approaches the area, and with the loss of heating this evening the chance for much strong convection will diminish. So far, updrafts are quite weak and appear to be fighting weak mid level lapse rates. The best chances for thunderstorms will continue to be north of I-16, as the cumulus field south of there is quite muted. Areas where the better coverage is expected coincidentally have the lowest DCAPE values, so the overall severe threat remains low. Depending on how boundary interactions work out, we could still see a couple strong to marginally severe storms. Tonight: Models show subtle shortwave ridging building across the forecast area and with the loss of diurnal heating there shouldn't be much of a source for nocturnal development. We could still see isolated to widely scattered showers and storms over the coastal waters, though the best chances for that will be over the Gulf Stream. Any lingering convective debris clouds should gradually thin through the night and westerly flow will prevail. Forecast lows are in the mid to upper 70s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Sunday: Mid-level heights increase slightly this period ahead of shortwave energy digging across the Great Lakes into the Ohio Valley. Rain chances will be low with a dry, deep westerly flow keeping the sea breeze circulation pinned until very late in the day. This combined with poor mid-level lapse rates and decreased surface based instability will support pops below normal for mid/late August. 20% pops look reasonable for most areas with 30% along portions of the lower South Carolina coast where low-level convergence will be locally enhanced with the resultant. It is very possible that little, if any, meaningful convective activity could occur and pops may be need to be lowered even more in subsequent updates. Highs will range from the upper 90s across the interior to the lower 90s at the beaches. Any lingering convection will quickly diminish after sunset with dry conditions prevailing overnight. Lows will range from the mid 70s inland to around 80 at the beaches and Downtown Charleston. Monday: A backdoor cold front will drop south through the area Monday morning and stall out across southern Georgia during the afternoon as it become intermingled with the sea breeze circulation. Although a somewhat cleaner/drier airmass will ooze into parts of Southern South Carolina behind the front, a significant airmass change is not expected across Southeast Georgia where conditions will favor isolated-scattered showers/tstms within a moderately unstable atmosphere. The best rain chances will occur south of I-16 and closer to the Georgia coast where low-level convergence will be maximized along the cold front/sea breeze intersection. 20-40% pops look on track for Southeast Georgia with pops below mentionable thresholds across most of Southeast South Carolina. Highs will range from the lower 90s along the I-26 corridor to the mid 90s across Southeast Georgia with cooler conditions at the beaches. Although isolated convection could linger through sunset across the far southern counties, mostly dry conditions are expected Monday Night. Could see isolated, low-topped showers move inland from off the Atlantic after midnight and affect portions of coastal McIntosh county, however confidence in this scenario is rather low this far out. Tuesday: Frontal remnants will gradually dissipate across southern Georgia during the day, but will remain the primary focus for isolated-scattered shower/tstm development during peak heating. A dry/stable airmass across Southeast South Carolina should inhibit convective development north of the Savannah River with pops south of the Savannah River ranging from 20-40%, highest along the Altamaha River. Highs will top out in the lower 90s away from the beaches, possibly a bit cooler north of the I-26 corridor. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... High pressure will prevail through this period. Through late week, the high will provide a continued respite from the relentless heat and humidity of recent weeks. Highs in the upper 80s to lower 90s will be accompanied by dewpoints in the 60s north of I-16 and not far above 70F farther south. Tuesday and/or Wednesday night, temperatures could even dip into the upper 60s at some inland/northern locations. The relatively dry/capped environment will remain hostile for deep/moist convection, and POPs are limited to isolated/scattered showers which could push onshore into far southern counties. Next weekend, a transition to highs in the lower/mid 90s and increasing dewpoints/greater instability could support an increased chance for afternoon/evening showers/ thunderstorms. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... VFR conditions are expected to prevail. At KCHS, the best chances for thunderstorms will be in the late afternoon and early evening but overall confidence is too low to include in a prevailing or even TEMPO group. Thick mid level clouds could end up reducing the potential all together. At KSAV, overall chances are lower and the forecast still does not include VCTS. The thinking is that thunderstorms will stay north of the terminal. Otherwise, the overnight is expected to be quiet. Winds will turn more southwesterly late today, but then go back to more westerly by Sunday morning. Extended Aviation Outlook: Thunderstorms could produce brief flight restrictions at both terminals Sunday afternoon/evening and at KSAV Monday-Tuesday PM. Otherwise, VFR. && .MARINE... Tonight: Assuming that convective outflow from evening storms don't disrupt the prevailing synoptic setup, southwest to westerly flow will persist through the night mainly around 15 knots. There could be periods of 15-20 knots, but conditions are expected to remain below Small Craft Advisory thresholds. Seas will range 2-3 feet, with some 4 footers possible in the outer reaches of the outer waters. Sunday through Thursday: Southwest winds as high as 15-20 kt are expected Sunday/Sunday evening ahead of an approaching cold front. Winds will veer to the northeast and east Monday as a cold front drops south. In the wake of the front, high pressure will build into the region and will provide east/northeast winds mainly 15 kt or less through late week. Seas will average 2-3 ft most areas Sunday through Tuesday, although 4 ft seas could occasionally develop over waters beyond 20 nm during this period. The long fetch/duration of east/northeast winds should push seas to 3-5 ft Wednesday/Thursday and there is a low probability for 6 ft seas to push into water beyond 20 nm mid to late week. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && NEAR TERM...BSH SHORT TERM...ST LONG TERM...SPR AVIATION...BSH/ST MARINE...BSH/ST
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHARLESTON SC 352 AM EDT SAT AUG 20 2016 AMZ330-350-352-354-374-GAZ087-088-099>101-114>119-137>141-SCZ040- 042>045-047>052-210800- CHARLESTON HARBOR- WATERS FROM SOUTH SANTEE RIVER TO EDISTO BEACH SC OUT 20 NM- WATERS FROM EDISTO BEACH SC TO SAVANNAH GA OUT 20 NM- WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND GA OUT 20 NM...INCLUDING GRAYS REEF NATIONAL MARINE SANCTUARY- WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND GA EXTENDING FROM 20 TO 60 NM-JENKINS-SCREVEN-CANDLER-BULLOCH-EFFINGHAM-TATTNALL-EVANS- INLAND BRYAN-COASTAL BRYAN-INLAND CHATHAM-COASTAL CHATHAM-LONG- INLAND LIBERTY-COASTAL LIBERTY-INLAND MCINTOSH-COASTAL MCINTOSH- ALLENDALE-HAMPTON-INLAND COLLETON-DORCHESTER-INLAND BERKELEY- INLAND JASPER-BEAUFORT-COASTAL COLLETON-CHARLESTON-COASTAL JASPER- TIDAL BERKELEY- 352 AM EDT SAT AUG 20 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS...SOUTHEAST GEORGIA AND SOUTHEAST SOUTH CAROLINA. .DAY ONE...TODAY AND TONIGHT. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ASSISTANCE IS NOT ANTICIPATED AT THIS TIME.
The Charleston,SC radar (KCLX), 35 km away, was scanning. The volume nearest the first event began at 22:47 UTC.
3 thunderstorm wind. Local standard time, as filed.
The South Carolina Highway Patrol reported a tree down near the intersection of Keans Neck Road and Kinloch Road.
The Berkeley County 911 Call Center reported a tree down across the 4000 block of Route 17A.
The South Carolina Highway Patrol reported a tree down on Mack Drive just north of Highway 17A near Jamestown.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Carolina in 2016Every state in 2016This day in weather historyWarnings in South Carolina, August 2016
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 653562, 653565, 653599.